A61B17/8033—Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates having indirect contact with screw heads, or having contact with screw heads maintained with the aid of additional components, e.g. nuts, wedges or head covers

A61B17/8033—Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates having indirect contact with screw heads, or having contact with screw heads maintained with the aid of additional components, e.g. nuts, wedges or head covers

A61B17/8047—Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates having indirect contact with screw heads, or having contact with screw heads maintained with the aid of additional components, e.g. nuts, wedges or head covers wherein the additional element surrounds the screw head in the plate hole

A61B17/8052—Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates immobilised relative to screws by interlocking form of the heads and plate holes, e.g. conical or threaded

A61B17/8057—Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates immobilised relative to screws by interlocking form of the heads and plate holes, e.g. conical or threaded the interlocking form comprising a thread

Abstract

A strain washer (1) rigidly secures bone screws (15) in a bone plate (20) having several bores (21). The cylindrical strain washer (1) has a central axis (2), a central bore (3) with an inner thread (4) for receiving the bone screw (15), a lower section (5) with a surface (9) resting on the bone and an upper section (6). The upper section (6) is shaped in such a way that it may be introduced from below into the bore (21) of the bone plate (20). The mean circumference of the lower section (5) is smaller than the mean circumference of the upper section (6). This design allows this strain washer to be used with any type of bone plates (20) and bone screws (15). The strain washer (1) may be selectively set at any desired position of the bone plate (20) and acts at the same time as a spacer for reducing the contact surface between the bone plate (20) and the bone.

Hier will die Erfindung Abhilfe schaffen. The invention aims to provide a remedy.

Der Erfindung liegt die Aufgabe zugrunde eine Gegenspannscheibe für die Plattenosteosynthese zu schaffen, welche mit jedem beliebigen Typ von Knochenplatten und Knochenschrauben, sowie wahlweise an jeder gewünschten Position (Bohrung) der Knochenplatte eingesetzt werden kann und dabei gleichzeitig als Abstandshalter zur Verringerung der Kontaktfläche zwischen Knochenplatte und Knochen wirkt. The invention has for its object to provide a lock washer for the plate osteosynthesis which the bone plate can be used with any type of bone plates and bone screws, and optionally, at any desired position (hole), and at the same time as spacers to reduce the contact surface between the bone plate and bone acts.

b) Bei einem Knochendefekt in der nahen Kortikalis, wie er beispielsweise bei einem Schraubenbruch im Knochen auftreten kann. b) When a bone defect in the near cortex, as may occur, for example in a screw fracture in the bone.

Claims (15)

Lock washer (1) for rigid fixation of bone screws (15) to a
bone plate (20) which exhibits multiple bore holes (21), whereby
the cylindrical lock washer (1) provides a central axis (2), a
central bore hole (3) with an internal threading (4) that
integrates with a bone screw (15), a lower section (5) with a
bone adjoining surface (9) and an upper section (6), whereby in
case of use of the lock washer (1) the upper section (6) is
locked in the bore hole (21) of the bone plate (20),
characterized in that the middle circumference of the lower
section (5) is smaller than the middle circumference of the
upper section (6).

Lock washer (1) according to claim 1, characterized in that
the interior threading (4) is fully accommodated in the lower
section (5).

Lock washer (1) according to one of the claims 1 or 2,
characterized in that it tapers continuously or not continuously
from the upper section (6) towards the lower section (5).

Lock washer (1) according to one of the claims 1 to 3,
characterized in that the upper section (6) provides at least at
the surface (7) which is adjacent to the bone plate (20) a
roughness of structure to improve the torsional strength.

Lock washer (1) according to one of the claims 1 to 4,
characterized in that it is shaped symmetrically.

Lock washer (1) according to one of the claims 1 to 4,
characterized in that it is shaped asymmetrically.

Lock washer (1) according to one of the claims 1 the 6,
characterized in that the surface (9) adjoining the bone is
smaller than the average cross section being perpendicular to
the axis (2) of the upper section (6).

Lock washer (1) according to one of claims 1 to 7,
characterized in that it is shaped ellipsoidally.

A fixation device with at least one lock washer (1) according
to one of the claims 1 to 8, a bone plate (20) with an underside
(23) and an upper side (24), which are penetrated by bore holes
(21), as well as at least one bone screw (15) with a head (16),
a shaft (17) and an exterior threading (18), whereby in case of
fixing the fixation device the upper section (6) of lock washer
(1) can be brought to a stopped position in bore hole (21).

Fixation device according to claim 9, characterized in that
at least one of the bore holes (21) provides a conical section
(26) that widens toward the underside (23) which is shaped in
form-locking fashion with the geometry of the upper section (6)
of lock washer (1) and in case of fixing the fixation device the
upper section (6) of the lock washer (1) is brought to a stopped
position.

Fixation device according to claims 9 or 10, characterized
in that at least one of the bore holes (21) of bone plate (20)
provides at least at the surface that is adjacent to lock
washer (1) a roughening or texturing to increase the torsional
stability.

Fixation device according to claim 11, characterized in that
the roughening or texturing is shaped in form of a tapering
conical section (26) of the bore hole (21).

Fixation device according to one of the claims 9 to 12,
characterized in that at least one of the bore holes (21) of
bone plate (20) is at its narrowest width (29) equipped with
securing pieces for lock washer (1) that are configured as
elastic nipples (25).

Fixation device according to one of the claims 9 to 13,
characterized in that the upper section (6) of the lock washer
(1) is form-lockingly insertable from below into the bore hole
(21) of the bone plate (20).

Fixation device according to one of the claims 9 to 14,
characterized in that the upper section (6) of the lock washer
(1) is shaped such that it is torsional securedly insertable
into the bore hole (21) of the bone plate (20).